Apparatus for rolling sheet metal



F. o. wADswoRTH 2,160,767

' APPARATUS FOR ROLLING SHEET METAL May 30, 1939.

7 sheets-sheet 1 Filed Sept. 6, 1935 Hll lll/

May 30 1939 l v l F. L.. o. wADswoR-rH 2,160,767

APPARATUS FOR ROLLING SHEELI METAL Filed Sept. 6, 1935 7 Sheets-Sheet 3May 30, 1939. F. 1 o. wADswoRTH 2,160,767

APPARATUS FOR ROLLING SHEET METAL l Filed Sept. 6, 1955 '7 Sheets-Sheet4 7 sheets-sheet 5 Filed Sept. 6, 1935 I s l v F. L. o. wADswoRTHAPPARATUS FOR ROLLING SHEET METAL May 30, 1939.

May 30, 1939. F. L. o. wA-DswoRTH 2,160,767

FPARATUS FOR ROLLING SHEET METAL l Filed sept. e, 1935'. 7 sheets-sheet6 Eg vmmf AMay 30, 1939.

F. 1 .l o. wADswoRTH APPARATUS FOR ROLLING SHEET METAL Filed Sept. 6,14955 Eg. m.

j NVE NTOR Patented May-30, l1939 l PATENTv OFFICE APARATUSFOR ROLLING'SHEET METAL Frank L. 0. Wadsworth, Pittsburgh, Pa.; Mildred I administM. Wadsworth ratrix oLFrank L. 0.

Application September 6, 19.35, Serial No. 39,437

v14 Claims.

My invention relates to the art of rolling metal, and, broadly stated,the purpose of my improvements is`to concurrently increase theeifectiveness, and reduce the cost, ofth'is operation, par- 5ticularly'in connection with the production of ,strip and siieet'products.

It is well known to rolling mill engineers that the reactive' pressureonl the rolls, and -the amount of power required to drive-them are bothl dependent on `the diameter of the'working surfaces, or,'moreaccurately stated, on the zonal arc of contact'between them and thematerial on which they are operating; and that a decrease in4 this arcof vcontact-within the limits l5 imposed byj securing theV necessarypull l 'or" biteis accompanied` by many advantages. But it-hasheretofore been found to be impossible to reduce the sizeof the rollelements below a certain value because of the torsional and transversebendingstresses to which they are subjected and because oi. theirresultant angular and lateral distortion. 'I'he last of these twodimculties may be overcome, or avoided, in part, by the use of a properarrangement of large backing rollsas exemplied in four high and clustermills-but the first mentioned obstacle toa reduction in roll diameterhas not, as far as I am aware, been previously removed.

It is the object of my present invention to elim-J inate, in whole or inlarge part, both of the diillculties above outlined; and to make itpossible to make usel of working rolls, which are, proportionally, ofmuch smaller sizethan have heretofore been employedL in plate (sheet orstrip) rolling; and which can be. operated more effectively andeicle'ntly than the larger working elements.V

I accomplish these results by a combination of an improved system ofbacking rolls-to withstand both vertical and horizontal stresses o n theworking rolls-with a new method of driv- 40 ing these elements wherebyan equalivzed, or automatically balanced, torque is applied to bothendsV of e'ach of the working rolls, and a uniform- 1y distributeddriving force is alsol applied to, .and through their entire length ofcontact with the material; and all tendencies to either bend orftwistthe'smali roll members are successfully resisted, or substantiallyeliminated.

'I'he manner invvwhich I apply power to'the w working rolls of myimproved mill diilers from that `of present day practice in two major,and -onejminor respect. I apply a positive gear drive to both ends ofeachworking roll, and automatically -balance, or equalize, the dualtorque, thus u exerted, by using reversely cut helical gears at theopposite ends of the driven members, which are left free to move axiallyuntil the pressures on the oppositely inclined gear teeth'aresubstantially the same; and I also apply a uniformly distributedfriction drive to the entire length 5 ofthe working rolls, which issufiicient in itself to eil'ect their desired movement during therolling operation. I obtain this last described characteristic ofdriving action by applying the main V source of power to the largebacking rolls of the 10 mill, and positively connecting 'these drivenmembers to theuworking rolls-through the use of the helical gears abovementioned-so that theseA intergeared elements are revolved at the sameperipheral speed, and any circumferential 16 slip between their engagedfaces is prevented.A

Under such circumstances the coeillcient of trac-v tion (friction)between the driving and the drivenroll elements is much higher than whensuch slip is permitted; and is, in eifect, equal to the 20 coeillcientof static friction between metal Isurfaces. For steel-on-steel thiscoeilicient varies from 0.25 to 0.5 according to the degree of pressureengagement and the condition of the engaged surfaces (wet orv dry etc);and under the 25 average conditions of rolling mill work it may be takenas at least 0.25. The horsepower that may be transmitted to the workingroll by its nonslipping frictional engagement with the positively drivenbacking roll is, under these condi- 30 tions H.P.= M PSA/53W where P isthe total pressure of the working roll on` the backing roll (or rolls)and S is the peripheral speed in feet per minute.

In cold rolling of strip and sheet productsthe pressure P varies from5,000 to 35,000 (or more) lbs. per inch of width. of thematerial-according to the percentage of reduction at each passand thespeed S varies from 300 to 900 (or more) ft. per minute. For a meanpressure of 20,000 lbs. and a mean speed of 600 ft. per minute thehorsepower that may be transmitted to the two (upper and lower) working.rolls from the two corresponding backing' rolls (by the non-slippingfrictional engagement between them) bey comes Y mission of power, by thenon-slipping frietional engagement of the positively driven backingrolls with the working rolls, is, of course, independent of the size ofthe latter; and thus permits the use of working rolls of very smalldiameter; and since this driving action is uniformly distributed overthe entire operative length of the working rolls any tendency to twistthe latter is substantially eliminated.

Another object of this invention is to dispense with all ball or rollerbearings for either the working or the backing rolls of four high andcluster mills; and to provide improved forms of plain cylindricalbearings therefor, which will have a very low coefllcient of frictional.resistance, and which will be more precise in their control of thethickness of the rolled product, and more uniformly reliable incontinuous operation than any anti-friction (sic) bearings of the typesnow in use. The attainment of this object is facilitated by theemployment of my improved plan of driving the working rolls (supra), andthe resultant possibility of making these rolls of much smallerdiameters than can be otherwise used; because, `as already stated, thedecrease in the arc of contact in the rolling operation reducesin astill greater ratio-both the working pressure and the power required toeffect a given percentage reduction in the thickness of the rolledproduct. v

Still another object of these improvements is to provide an arrangementof working and backing rolls-for four high and cluster mills-which willmaintain' all of the revolving elements in continuous pressureengagement with each other-regardless of whether material is, or is not,passing through the mill-and which will also permit of the easy removaland replacement of the working rolls without ldisturbing the mounting,or the adjustments of the backing rolls, or of the driving mechanismtherefor. An ancillary purpose of my invention is to provide a freelyiloating mounting, or support, for the working rolls which will hold thelatter in definite andl precise alignment with each other and with theaxes of the backing rolls without the use of any end bearings orhousings; and without any attendant heating (slight though it may be) of the usual neck portions of these rolls.

Other objects and advantages of the present improvements will becomeapparent to those skilled in this art, by the following description of-.several illustrative embodiments thereof, which are illustrated in theaccompanying drawings in which: 1

Figure I is an end (or side) elevation of a four high mill whichembodies the main structural and operative features of my invention;Fig. II is a vertical sectional elevation on the plane II-II of Fig. I;Fig. III is an enlarged sectional view on the bent piane III--III ofFig. I; Fig. IV is a composite section, (on a much enlarged scale) onthe two planes IV and IVa of Fig. III; Fig. V is another sectional viewon the plane III-III of Figs. I and VI; and Fig. VI is a transversesection on the plane VI-VI of Fig. V.

Fig. VII is a composite vertical section through a second form offour-high-semi-cluster mill which also embodies my improvements-theright hand half of this view being taken on the plane VII- VII of Fig.VIII, and the left hand portion thereof being taken on the planeVIIa-VIIa of that iigure; Fig. VIII is a reduced scale view, partly insection, on the plane VIII-VIH of Fig.

VII; Fig. IX is a partial section on the plane ancona? IX-IX of Fig.VII; Fig. X is another reduced scale section` on the plane X-X oi.' thissame gure: Fig. XI is a side (end) elevation of the mill shown in Figs.VII to X, inclusive; Fig. XII is a partial front view of this sameconstruction; Fig. XIII is a very greatly enlarged section (aboutone-half fullsize), through the end portion of one of the working rolls(on the plane XIII-XIII of Fig, XI); Fig. XIV and Fig. XV are diagramsshowing the arrangement of certain elements of this second illustrativeembodiment of my invention, and also indicating an optional change inthis organization; and Fig. XVI is another diagram indicating anotherpermissible addition, or supplement, to the construction shown in Figs.I to VI inclusive. Y

Fig. XVII is a side or end view of a cluster mill, which is providedwith two pair of main backing rolls, and which exemplifies lanotherutilization of my present invention; Fig. XVIII is a compositeillustration of the construction shown in Fig. XV'II and is taken atright angles thereto, the right hand portion thereof being a plan viewand the left hand portion being a horizontal section on planeXVIII-XVIII of Figure XVII; Fig. XIX is a greatly enlarged section onthe plane XIX-XIX of Fig. XVIII; Fig. XX is a partial section on theplane XX--XX of Fig. XVII; Fig. XXI is another partial section on theplane XXI-XXI of this same figure; and Fig. )QUI is VVa partial endelevation of the opposite side o! the assembly shown in Fig. XVII.

Fig. XXIII is a side (end) elevation of a full cluster mill (providedwith two pair of main backing rolls of equal size) which constitutesstill another embodiment of my improvements; Fig. XXV is a partialsection on the plane )DUV- XXIV of Fig. XIUII; Fig. XXV is a fragmentaryend view of a part of this construction; Fig. XXVI is an enlarged viewof a part of the section shown in Fig. XXIV; Fig. XXVII is a compositevertical section, and elevation on the plane XXVII- XXVII of Fig. XXIII;Fig. XXVIII is a plan view, on a reduced scale, of the constructionshown in Figs. XXIII to XXVII, inclusive; and Fig. m is a diagramsimilar in character to those shown in Figs. XIV, XV, and XVI.

Fig. XXX is a vertical elevation of a mill construction, the right handportion thereof being an end view and the left hand portion being avertical section through the rolls intermediate their lengths; Fig. XXXIis a side sectional elevation on the plane HXI-XXXI of Fig. m; Fig.XXXII is a partial front view in elevation of the construction of Fig.XXX; and, Fig. XIQIIII is a semi-diagrammatic showing of a generalarrangement cf forming and backing rolls, and of a double system oftake-up reels.

The organization illustrated in Figs. I to VI, inclusive, comprises twosmall working rolls l and 2 a pairI of large backing rolls 3 and 4; andtwo pair of auxiliary supporting rolls 5 6 and 1 -8. Each of the workingrolls (l-2) is provided at both ends with helical gear elements, 9 andI0, which are preferably formed on structurally separate sleeves of asuitable alloy steel, and which are rigidly attached to the body of theroll, so as to form an integrally operative part thereof, in anysuitable manner. As here shown each gear sleeve or collar is bored tothe standard taper of a Morse drill shank, and is secured to thecorrespondingly coned end of the roll by three symmetrically positionedkeyways and splines and by a clamp nut Il (see Figs. III, IV, and V).The backing rolls 3 and 4 are each made up of a heavy body shell, I2,and axially adjustable bearing sleeve I3, and two end rings, I4 and I3,which are provided with helical gear teeth that are adapted to engagewith the gears 3 and I0 on the work rolls I and 2. The inner surfaces ofthe shell and sleeve members I2 and I3 are 'bored to a slight taper, andare rotatably engaged with the reversely coned surfaces of stationaryjournal members I6 I3 whose ends are adjustably mounted between theadjacent edges of U-shaped housing pillars, 20-20 and 2I-2I, that form apart of the main supporting frame of the assembly. v'Ihe tapered bearingsleeves, I3 I3, are held in adjusted position with respect to the bodyshells I2 I2 by means of a circumferentially disposed series of bolts,22, see Fig. II, which are located in slots on the outer surface of thesleeve member I3, I3, and are threaded into the central portion of theshell members I2 I2. 'I'hese bolts are provided with enlarged collars,or heads, 24, which are seated in pockets on the intermediate flanged orshouldered portions of the internally tapered bearingsleeves I3 I 3; andterminate in flattened or squared ends 25 by which they may be turnedtomove the sleeves axially in the surrounding shells I2, and therebyadjust the bearing clearances between the members I2 I3 and I6.

The gear rings I5-I5 are clamped in position on the right hand ends ofthe' backing rolls 3 and 4, by means of nuts 23, which are threaded onthe bolts 22 (which pass through three rings); and the gear rings I4 I4are correspondingly secured to theopposite ends of the backing rollshells I2 I2, by means of the cap screws 21. The rings I4 I5 areprovided with helically cut gear teeth of relatively fine pitch (e. g. 5D. P.)- Whlch, as already stated, are in engagement with the helicalpinions on the corresponding ends of the work rolls I and 2 and therings I4 I4 are also provided with worm teeth of much coarser pitch,which are engaged with double or triple threaded driving Worms 23-28,that are secured to a vertical shaft 30, and are connected to a suitablehigh speed motor by a pair of mitre gears 3I 3I.

As indicated in Fig. I which illustrates a roll assembly for anon-reversing, or continuous, four high mill-the work rolls I and 2 arepositioned behind the vertical plane in which the axes of the backingrolls 3 and 4 are positioned; and there is, therefore, a horizontalcomponent of the holding down pressure on the working rolls whichresists their tendency to climb or be drawn forward on the materialentering the roll pass.v By properly positioning the axes of the rollsI, 2, and 3, 4, the rst named elements may be held in substantiallystable equilibrium under any given fixed conditions as'to draft (viz.percentage of reduction) and otherl factors of resistance to rolling;and provision is made-as hereinafter explained--for adjusting theVrelative positions of these roll axes. But these conditions may, anddo, change duringV the rolling of successive sheets, or even differentportions of thesame sheet; and I therefore provide the system, orassemblage of auxiliary supporting rolls 5 6 and 1 3, fortheis mountedas a unit on, or in a heavy U-shaped chock or bearing block 33 (bestshown in Figs. V

and VI) which'is adjustably clamped to the reary housing pillars 2I 2I,and is connected to the front housing pillars 20-20 by the tension`bolts ments transmitted by the two pair of helical gearsl is 34. Theauxiliary rolls l and 1 are loosely mounted on end pivot bolts 3lv thatare carried by the side legs of the blocks 33; and the cooperating rollsl and 3 are rotatably supported in semi-cylindrical bearing pockets 36in the base of these blocks. The adjacent surfaces of the rolls 5 3and-1 4 revolve in opposite directions, and the end pivot guides 3B aretherefore so positioned that these rolls are never in contact with eachother; but the surfaces of the rolls 6 and 3 move in the same directionas the adjacent faces of the main backing rolls 3 and 4; andthe chockblocks 33 ,33 are, therefore, preferably so adjusted as to exert aforward pressure on the working rolls I and 2 through the intermediateidle rolls 5 and 1 and to concurrently establish and maintain a pressureengagement between the rolls 6 3 and 8 4. Under these conditions theWork rolls I and 2 will oat" inthe shallow crotch between the mainbacking rolls 3 and 4 and the intermediate supporting rolls 5 and 1; butin order to further guard against any possible sidewise displacement ofthe work rolls from their stabilized oating position the ends of thegear sleeves 9 and III are loosely embraced between the notchedextremities of the' U-shaped supporting members 33 and the cap members31 which are secured thereto by nuts on the tension bolts 34.

The journal supports I6 of the main backing rolls`3 and 4 extendoutwardly between the adjacent sides or edges ofthe U-shaped housingpillars 20 and 2l and are provided with oppositely projecting lugs 40 40which are threaded to engage with two pair of lifting and holding downscrews 4| 4I that are suspended in upper bearings on the housing caps 4242, and are concurrently rotated,'in. opposite`directions, by the wormwheels 43 43 and the intermediate worms 45 45. Each screw is providedwith oppositely threaded portions which respectively engage the lugs onthe upper and lower journal members I6 I6; so that the rotation of thesescrews moves the journal members-and the backing rolls 3 and 4 carriedthereby-toward or away from each other, and correspondingly varies thevertical opening between the working rolls I and 2. The two worms 45-45,are respectively secured to the coaxial sections 43-46a of a two partshaft, and may be connected to, or disconnected from, each other by anintermediate clutch connection 41, so that all four screws may bemovedsimultaneously, or each pair of screws (at one or the other side of theroll stand) may be moved independently, to obtain and maintain exactparallelism of the roll surfaces.

When power is applied to positively rotate the backing rolls 3 and 4 inopposite directions (through the gears 3I '3I, the shaft 30 and thereversely threaded worm and worm wheel elements 28 23)"the movement. ofthese rolls is communicated to the work rolls, I and 2, in part by thereverselycut helical gears on the rings I4 and I5, 'and the sleeves 9,III-which compel the rolls I 2 3 and 4 to rotatev at the samevperipheral speed-and in part by the non-slipping frictional engagementof the roll surfaces which are ground to the same diameter as the pitchline dimensions of the helical gear ele- The amount of power which canbe not in itself sufficient to drive the small working rolls of alargecapacity mill-e. g. one 5 D. P. helical gear of '4" face running ataperlpheral speed of 600 ft. per minute (supra) can safely transmit lessthan 30 P. (under average conditions of mill operation) and four suchgears cannot be depended upon to transmit more than 120 H. P.-but, asalready pointed out, the nonslipping frictional pressure engagement ofthe backing rolls with the 'working rolls is capable of transmittingample additional power (e. g. in the example already considered upwardsof 3600 H. P.) to drive the working rolls under very heavy drafts and athigh speeds. The primary function of the helical gear connections is nottherefore to supply power to the working rolls, but is to maintain thelatter in non-slipping relation to the power driven backing rolls andthereby obtain and maintain a high coeiilcient of friction (i. e. oftraction) between the engaged surfaces.

It may be noted again that the power which is transmitted from the largepositively driven backing rolls to the working rolls-by the nonslippingfrictional engagement of these elements-is uniformly distributed overthe entire width of the material being rolled; and it has therefore notendency to twist or tortionally strain the working rolls even when theyare made of very small diameter. Such additional amounts of power as maybe transmitted to the working rolls, by .the helical gear trains, 9-I0-III-IS is equally divided between the two ends of the rolls, because ofthe opposite and complementary inclination of the helical gear teeth,and because the work rolls are free to move axially until the opposingend thrusts on these teeth are balanced and equalized by such movement.In order to permit each work roll to "hunt" its proper position, withoutinterference from the other, the driving worm shaft 30 is provided witha movable end thrust bearing 48, which is preferablyso adjusted that theteeth of the work roll gears are out of operative contact with eachother (see Fig. IV) and cannot, therefore, exercise any controllingeffect on the axial equalizing movements of either roll.

It will be observed that the length of the journal bearings for thelarge backing rolls is substantially greater (e. g. as shown in Fig. I,greater) than the width of the pass be- -tween the work rolls; and thatthe mean diameter of their bearings is nearly fifteen times that of therolls I and 2. For a. work roll diameter of 2.6" (13 teeth of 5 P. D.)the projected area of each of these bearings is therefore about 69 sq.in. per inch of width of the roll pass; and if the mean pressure is, asbefore assumed, 20,- 000 lbs. per inch, the unit pressure, per squareinch of projected bearing area, is less than 290 lbs. Now it is wellknown that under such relatively light unit pressures the coemcient offriction of a well made cylindrical journal bearing, operati-ng at therelatively low surface speed here under consideration (about 450 ft. perminute), is under proper conditions of lubrication, not over 0.0015 to0.002, which is less than the average coeflicient of a well designedroller bearing operating at its maximum safe load. With a copious supplyof heavy lubricant plain journal bearings may be subjected to a load of1000 lbs. or more per square inch of projected area without rupturingthe wedge shaped oil illm whose maintenance is necessary to obtain a lowcoeillcient of friction; and the form of bearingA illustrated in Figs. Ito VI is, therefore, capable of operating continuously and efficiently,Without undue heating, under any load to which it may be subjected inpractice.

In order to keep the journal bearing surfaces continuously ushed withoil, one, or both, ends of each journal member I6 is provided with alarge reservoir 49, which is kept lled with lubricant under pressure,(e. g. by a pump, or from an overhead tank, not shown), and is alsoprovided with a central passageway 50, which communicates with thisreservoir through a valve controlled port 5I, and which is connected tothe surface of the bearing bya series of radial ducts 52--52 that leadto points about 90 degrees in advance of the projected planes of thruston tlie backing roll members 3 and 4. The oil which is carried around bythe revolving shells I3 collects in shallow pools at the bottoms of therolls, until it reaches;l depth indicated by the dotted lines, a-a,(Fig. II), and is then syphoned oif through the passageways 53-53, anddischarged into sump cups 54 from which it is drawn through theoverowpipes 55 and returned to the main supply pump or tank. Thereservoir 49 in the upper journal I6 is also provided with a feed pipe56 which leads therefrom to the branch pipes 51-58 that communicaterespectively with the passageways 60 in the upper and lower chock blocks33-33. From these passageways a continuous supply of lubricant isdelivered to the advance edges of the bearing pockets in the blocks 33.In order to keep the surfaces of the auxiliary rolls 5-6-1 and 8 freefrom scale and dirt I preferably provide wiping pads BI-BI which areremovably supported on the blocks 33 by cross bars 62--62, see Fig. IV.I also provide for a continuous lubrication of the helical gear teethand of the driving worm teeth on the rings I4 and I5 through a series ofsmall passageways 63-63, see Fig. II, winch lead from the annularchannel Abetween the backing rolls members I2-I3 to the outer surfacesof these rings; and the driving worms 28-2-8 are also preferably coveredby segmental shields (indicated by dotted lines in Fig. I) which may becharged with hard cup grease.

Under normal conditions of operation the back pressure on the rolls 6and B is relatively very small (as compared with the vertical pressureson the rolls 3 and 4); and the unit load on the bearing areas for theauxiliary supporting rolls 6 and 3 is, therefore, even less than it ison the main backing roll journals.

It is obvious that the use of ball or roller bearings for the variousrevolving elements of my improved roll system would present noadvantage, because it would not result in any saving of power, or anyreduced heating of the bearing parts, while the mill is in operation;and because the increased initial starting friction, which is involvedin the use of plain bearings, is a matter of no consequence when thedriving powerl is applied directly to the backing rolls, and transmittedfrom them to the working rolls. On the other hand the use of plainbearings, with an extended area of bearing surface, is of materialadvantage in the attainment of precision results, (as has been fullydemonstrated in the operation of machine tools), and in the avoidance ofextreme elastic distortions or deformations, of the bearing elements.And even if the heating of the plain bearings of my improved millshould, at any time, temporarily exceed that of the usual form of neckroller bearings-by reason of insufficient lubrication and a consequentrupture of the oil films-the effect of such increased heating isinconsequential because it is uniformly distributed over the entireworking length of the backing rolls and cannot therefore produce anyoccur when these rolls are supported. in the usual manner, in end neckbearings. The amount ot power required to overcome the frictionalresistance to .rotation per se, is, in any case, insignificant ascompared with that required to effect the plastic deformation of thematerial being rolled.

Either one, or both, of the work rolls I and 2 may be readily removedfrom either side (end) of the roll stand by slightly separating'thebackfing rolls, and detaching .the cap plates Il ll.

The intermediate idle rolls! and 'I may then be taken out by withdrawingthe end pivot bolts tI-Sg; and this, in turn, permits the auxiliarysupporting rolls 6 and I to be removed from their bearing pockets in thechock blocks 33, without disturbing the arrangement of the adjustmentsof any of the other parts of the assembly. Either one of -the chockblock members-together with' all of the rolls supported thereby-may alsobe withdrawn from the rear side voi' the roll stand by removing theseveral bolts and cap screws, by which it is clamped to the rear housingpillars 2l-2I, and uncoupling the oil pipe connections 56--51-58, Itrequires, therefore, very little time to remove any of the small rolls.when they become unduly worn and replace them by others; and in doingthis the helical gear sleeves 9 4and I--which are not subject to anysevere wear-may be used with a number of successively regrooved orrenewed working rolls of substantially the same diameter.

The construction illustrated in Figs. VII to XIV,

' inclusive, is of the same general character as that shown in Figs. Ito VI; but differs therefrom in various structural details. In thissecond illus'- trative embodiment of my invention the work rolls la and2a are positioned a substantial distance behind the axial plane of thetwo main backing' rolls 3a and la; andare directly engaged on their rearsides by two secondary backing rolls 65-65 (which are of materiallygreater diameter than the supporting rolls B `and l of the previouslydescribed organization), that are out of contact with the rolls 3a and4a (see enlarged view of Fig. XIV). Each working roll is, in this case,supported ina relatively deep crotch between the surfaces of a main anda secondary backing roll (laf-65, or ct-85); and does not, for thatreason, require any end guides, or other restraining means, to hold itagainst accidental lateral deplacement when the mill is running idle.

In this respect the construction now under consideration partakes of thenature of a cluster mill, although the rolls laf-Qa and II are ofmaterially different diameters.'

Each of the working rolls la and-2a is of substantially the sameconstruction as that of the rolls I and 2; i. e., it comprises a body'portion, and two end sleeves 9a and Ila which are provided withoppositely inclined helical gear teeth. and which are rigidlyl securedto the body porition in the manner already described (supra). Each mainbackingv roll (3a or 4a) comprises a massive cylinder I1 of shaped crosssection, and two 'forged steel rings Ila and iavof L cross section,which are `rigidly attached to the central enlarged portion of thecylinder 61 by the cap bolts 21a-21a etc. Each set of rings is projvided with oppositely inclined helical gear teeth which are adapted t'omesh with the corresponding gears on the associated work rolls sleeves;

scribed.` The end portions of the hacking .roll cylinders l'l--Il arerotatably' supported by mas'- sive chock blocks I0-1I, whichl are eachprovided with a pair of side luss. that are' embraced by the legsl ofthe channel shaped housing pillars Ila-Ma, and are threadedto engage theverticallifting andjholding down screws lia-4in.

Each chock block 'Il carries a split tapered bearing sleeve I I, whichis seated in a reversely coned socket in the chock block, and is held inan axially adjustable position thereinby the face rings '12, and the capscrews 18. The right hand ends ofthe backing roll bodi 'I-Ol areextended outwardly, beyond the bearing 4sleeve members 1i-12, to receivea pair of large spur gears, (or herringbone gears -1!) which'are drivenin unison from any suitable source ofv are each provided with rightand'left hand threaded portions,l which respectively engage the lugs onthe upper and lower `chock blocks 'III- 10; and are rotatably suspended-in bearings onthe cross heads 'I6-16 that connect the upper ends of thehousing columns a-2| a. -If desired the lo er ends of these screws mayalso be provided end thrust bearings 11 (see Fig. V11) which will assistin supporting the weight of the suspended backing rolls and chock blockbearing members. 'I'he upper ends of the screws l Ia4 la etc. areprovided with bevel gears 'Il which are cross connected, in pairs, bythe bevel pinions and shaft elements 19-19-80; and the shafts, 80-80, atthetwo ends of the roll stand, are coupled together by two sets of bevelgears and pinions 8I-82, and by a third counter cross'shaft 46a. Theshaft 46a. is provided, at each end, with a large hand wheel 83; and ismade in two sections (like-the shaft 46), that may be con` nected to, ordisconnected from,each other by a central clutch member 41a, so as topermit of concurrent or independent operationof the' screws at theopposite ends of the -backing'roll' M are secured in a horizontally xed,but

verticallyadjustable,v position on the rear housing pillars lia- Zia bythe cap bolts kIB---II etc.-

In the arrangement of rolls shown in Figs. VII

to m, inclusive, the vradial thrust' on the main vbacking roll bearingsis about98% of the vertical l.spreading pressure on. the working rollslav and 2a. But the bearings ofthe secondary backing mus et arealsosubjected to a'r'adial thrust-which necessary area `is obtained bymaking surfaces of the `iull diameter, and ofthe entire length, of therolls (which, as shown in Fig.

X extend the full distancel betweenthe inner vsides of the housingpillars 2id-lla). desirable toutilize this relatively heavy pressureengagement between the secondary backing rolls I6, Il, and the workrolls, Iaand 2a, to supplement the frictional transmission of-power tothe latter: and,v in the construction now under consideration, I do thisby providing means for driving'the secondary rolls from the mainbackingv But itis also;

rolls 3ay and la. scribed:

As already lstated the helical gear rings Ida-lia are provided withplain cylindrical extensions 98 which are in circumferential registrywith the outer ends of the secondary backing rolls 65, and the adjacentplain (untoothed) portions of the gear sleeve elements 9a and i0a. Allof these last named sections are ground down to a diameter slightly lessthan that of the central body portions of the rolls, and are engaged bythinvendless steel bands 89-90 (not shown in Figs. VI to X, butdiagrammatically illustrated in Figs. XI to XIV), which are preferablymade of some alloy of high tensile strength and high elastic limit (suchas that used for band saws), and which are maintained in drivingengagement with the said sections by adjustable tension rolls 9i-9|. Onepair of these steel bands (B9-99) engage with the outer halves of theprojecting anges 6.8 on the lower backing roll 4a; pass up through slots92 in the block 8l and around the lower secondary rolls 65; then underand around the lower work rolls 2a, then up and around the upper workroll la, then forwardly, along the contiguous surfaces of the upper andlower main rolls 3a and 4a, to the lower tension roll 9i, and thence tothe advancing surface of the roll la (as shown by the heavy line in Fig.XIV) 'I'he cooperating pair of driving bands -90 are engaged by theinner halves of the ring anges 68, pass down through slots 93 in theupper chock block 84, and around the upper secondary backing roll 65,then vup and around the upper work roll la, then down and around thelower work roll 2a, then forward, (along the surfaces of the rollslll-3a) to the upper tension roll 9|, and thence, up and back, to theupper backing roll 3a (as shown by the broken dotted lines of Fig. XV).Each end of each working roll (la and 2a) ls therefore subjected to thedriving action of two bands-one of which passes around the roll in aclockwise direction, and the other of which passes around it in thereverse counterclockwise direction-and in order to automatically balanceor equalize these reverse pulls, the tension pulleys 9l-9|, are mountedon bell crank frames 94-94, which are journalled on cross shafts 95-95,that extend between the front housing pillars 20a-20a, and which areconnected by a common tensioning bolt 96. If desired heavy springs (nothere shown) may be interposed beta een the adjustable nuts, at one orboth ends, of the tensioning bolts 96, and the outwardly extending armsof the frames 94-94, in order to permit a slight elastic yielding of thetensioning devices; but the elasticity of the bands themselves isusually sufficient to provide for any necessary variations in lengththat may be produced by temperature variations etc. during the operationof the mill. It will be understood, of course, that a pair of these orother equivalent tensioning devices is provided at each end of the rollassembly; and that these devices may be adjusted concurrently orindependently to maintain either the same or different tensions in thetwo pairs or sets, of bands or belts that engage with the opposite endsof the connected rolls.

If the effective driving tension of each of the four steel belts 99-89and 90-90 is maintained at a mean value of 2000 lbswhich can be easilysustained by a thin (.04 to .05") alloy steel belt of 3.5 to 4 inwidth-the total amount of power that may be transmitted to each workingroll (Ia-or 2a) at a peripheral (rolling) speed 'Ihese means will now bedeof 600 `feet per minute will be approximately 36.4 H. P. for each beltor a total of over H. P. for the four. 'I'he amount oi power transmittedto both rolls is therefore over 290 H. P.

In order to permit these belts 89 and 90 to pass around the secondarybacking rolls 65, a narrow portion of the bearing surface on the upperside of the lower roll 65, and on the lower side of the upper rolls 65,must be cut away (as clearly shown in Fig. XIV) but this slightreduction in bearing area is in part compensated by the pull of thebands which tends to relieve the axial back thrust on the rolls andtherebyA reduce the resultant unit pressures on the bearing surfaces.This belt tension also reduces the reverse'radial pressures on the axesof the main backing rolls 3a and la; and correspondingly diminishes theunit pressures on the bearing sleeves 'll-H therefor.

All of the bearing surfacesboth those of the main backing rolls, 3a and4a, and of the secondary backing rolls, 65, BS-are continuously andcopi/ously flushed with oil under pressure from a large tank orreservoir 91, which is provided with pipe connections Blo-58a, that leadto longitudinally extending passageways Stia-60a in the chock blocks94-84'-from which the lubricant is supplied to the entire advance edgesof the semicylindrical bearing pockets in these blocks-and which islalso connected, by the vertical conduit 98 with the radial spaces 99-99,between the edges of the split bearing sleeves 'll-1|. The outer ends ofthese openings are preferably closed by adjustable screw plugs |00,which are carried by the face rings 12, and which are provided withpacking washers |0| of soft plastic metal (e. g. lead) that may beforced down over, and partially into the said openings after the sleeveshave been axially adjusted to provide the proper bearing clearancesbetween them and the rotating members 61-61. 'I'he lubricant is thenintroduced to the openings 99-99, and supplied to the advance edges ofthe sleeve bearings, 'li-1|, through the horizontal nipple connectionswith the vertical conduit 98. This conduit also supplies oil to theshaft bearings of the tension rolls 9I-9I, through pipes |03 andsuitable passageways in the cross shafts 95 and the arms of the bellcrank frames ill- 94.

'I'he amount of power transmitted to the secondary backing rolls 65-65,by means of the steel belt drives above described, isI less than half ofthat communicated to the working rolls Ia` and 2a by this samemeansbecause each of these secondary rolls is engaged by only two of thebelts, and the arc of engagement is also less than that of the beltswith the working rollsbut whatever power is thus transmitted to therevolving elements 65, is in turn transmitted to the elements la and 2aby the pressure engagement between their contacting faces.

In the upper part of the diagrammatic illustration of Fig. XIV, I haveindicated an additional means for communicating an added amount of powerto the upper secondary backing roll 65 and from it, to the cooperatingworking roll la. This means comprises a pair of idle helical gears |04,which are positioned in end pockets in the block 94 and are rotatablysupported on a cross shaft |05 carried thereby. 'I'hese gears |04-I04are in alignment with, and are engaged by, the helical gear teeth on themain backing roll rings Maf-wa. The secondary roll 65 is, in this case,somewhat reduced in diameter-(as compared with the construction shown inFigs. VII to XI, and also in the lower part of Fig. XIV)-and is y2,160,767 also provided with two rows of helical gear teeth,

roll, each of the idle pinions |04, |04 is left free to move axially onits supporting journal |05; and the secondary roll B5 is also permittedto move endwise in its bearings. Under these circumstances the engagedhelical gear elements, I III-IIrG-Qa and Illa, will automatically huntpositions in which the power transmitted from the main backing roll ringgears Maf-ld to the .work roll gears Sa--Illa is equally divided ordistributed between the two diiIerent zones of tooth engagement; andsince these zones are well separated--by an .angular amount greater thanthe arcs of tooth contact-the total amount of power that may be safelytransmitted by the engaged gear elements is double that which can betransmitted when there is only one zone of engagement-as is the case inthe organizations shown in Figs. I to XIII inclusive.

In the diagrammatic illustration of Fig. XIV,

I have shown the supplemental gear drive forthe secondary backing rolls,as applied only to the upper one of these members, but it will beunderstood without further explanation that when this'supplemental driveis used it will, preferably, be applied to both of the lower and theupper roll elements 85 and Sa-IIIa.

Under the conditions last described the total amount of power that maybe transmitted from the positively driven main backing rolls to theworking rolls is as follows:

(A) Through the helical gear connections (with gears of 4" face and of 5D. P. at a pitch line (rolling) vspeed of 600 ft. per min.

(a) By direct connection between n 9a-I0a, and Ila-Ilia (supra)- 120 H.P. (b) By supplementary connection through the gears IDI-|06--- 120 H.P.

(B) Through the belt connections 89 and 90 (a) By direct engagement withthe working rolls (supra) 290 H. P.

(b) By engagement with the secondary backing rolls 140 H. P.

.l 430 H. P.

It is obvious that the amount of power which can be transmitted from thepositively driven econdary backing rolls 65-65 to the working rolls Iaand 2a can be no greater than that which is communicated to the backingrolls themselves; and that in the case last considered this amount isVlimited .to the transmitting capacity of the helical gear and beltconnections IIM-IIIG and 89.-9II. I will now proceed to describe anothermore pronounced type of cluster mill, in which each working roll issupported by the large backing rolls of unequal size, and in which allof these backing coils are directly, and independently driven from acommon source oi' power.

The organization last referred to is illustrated in Figs. XIII to XXIIinclusive, and comprises two small'working rolls Ib- 2b Aof,substantially the same construction as those previously described; andfour large backing rolls b-lb and I IIIA-I I I; which are driven insynchronism (with the rolls 3b and I I0 revolving ina counterclockwise,and the rolls 4b and III revolving in a clockwise direction) by a trainof worm and worm wheel gearing, which will be later described.

In order to reduce the horizontal distance between the axes of the rolls3b-I I0 and lb-I I I,

the surfaces of these revolving elements are provided with aninterdigitated, or interdigitating.' series of tongue and groove, orcollar and channel, sections, II2--II3 etc., of which only the collarelements engage with the working surfaces of the rolls Ib and 2b. Thesections are each of relatively small width, and the staggered lines--orrather narrow bands-of pressure engagement between the working rolls andthe grooved backing rolls are so short, and are separated by such smallangular intervals, that there is no material tendency to bend, ortransversely deform, or circumferentially distort the smaller workingrolls. The projected areas of pressure contact between the revolvingelements isl in fact substantially the same as that which exists betweeneach of the working rolls and the single large backing roll of a fourhigh mill-such as is shown in Figs. I to VI inclusivealthough it is lessthan that which is obtained by the use of both `primary and secondarybacking rolls, in senil-cluster mills such as were last considered.

' The main backing rolls 3b and 4b are rotatably mounted on stationaryjournal members IBb, which are provided, at each end, with squaredextensions that are embraced and guided by the side flanges ofchannel-shaped housing pillars h-2lb, and are threaded to engage thelifting and holding down screws 4 Ib-l Ib. These screws are supportedand suspended in bearings on the housing caps 2b-42h, and may also beprovided,`

If desired, with end thrust step bearings similar to those shown in Fig.VII. They are rotated by means of worm wheels IM-I I4, which are crossconnected by a pair of worms I I5 on the two part shaft, I I6, that isprovided with a hand wheel at each end and with a clutch coupling,'l`lb,at the center; sothat the two screws may be operated concurrently orindependently as desired. "Each of the stationary journal members, IGI),is provided with two reversely tapered split bearing sleeves II1, II'I,which may be axially adjusted on these journal supports by means of acircumferentially disposed row of bolts II8, see Fig. XXII, that areseated in longitudinal slots on ythe periphery of the members I6b, andare adapted to draw together, thus expand, the spit sleeves tocompensate for wear. The opening between the edges of each expandedsleeve is substantially closed at one end, (see Fig. XVIII), by theadjacent inwardly projecting shoulder of the outer backing roll shell;and at the other end (see Fig. XXII) it is closed by a plug I00b,similar to that shown in Fig. IX, through which oil is introduced,preferably under pressure, from a suuply conduit 98b;the sleeves beingsopositioned that the lubricant so introduced is fed to v the revolvingbearing surfaces in planes about y90 degrees in advance of the projectedlines of thrust of the journal axes.

The secondary bearing rolls IIII and III are each carried by a massivechock block |20, whose ends are rigidly secured to the L-shaped housingpillars |2|-|2|, and whose central portion is bored out to form asemi-cylindrical grooved bearing surface for both the collar and thechannel sections of the associated roll member, and thus afford an amplebearing area to receive the backpressure to which it is subjected in therolling operations. This grooved bearing surface is constantly andcopiously supplied with oil through the longitudinally extendingpassageways 60h, (see Fig. HX); and the pipe connections 51a and 58athat lead to any suitable tank or reservoir. In order to prevent scaleor dirt from being carried into the grooved bearing surface suitablewiper pads 62h may be mounted on the advance edge of each bearing block|20.

The end collar sections of each pair of backing rolls, :ib-H0, and4b|||, are provided with trains of helical gear teeth |4b|5b and |24|25, which are of the same (pitch) diameter as the associated collarsurfaces, and which are adapted to engage with the elongated helicalpinions on the work roll sleeves 9b and |0b. These gear connectionscompel all of the cooperating rolls to revolve at the same peripheralspeed and thus maintain the pressure engaged surfaces thereof innon-slipping relationship to each other, so as to secure the mosteffective frictional transmission of power from the large positivelydriven backing rolls to the small working rolls. In order to obtain anequalized driving pressure between the gear teeth on the main backingrolls, 3b'||0, (or 4b-|||), and the teeth on the work roll sleeves9b-|0b, the latter are left free to huntl the proper axial positions (asbefore explained); and each set of backing roll elements (3b-I I0, or4b-ili) is driven in the same direction by a pair of right and left handworms |26|21 (or |29-|30) one of which engages a worm wheel |3| on theouter end of the backing roll 3b (or 4b), and the other of which engagesa worm wheel |32 on the adjacent end of the secondary backing roll ||0(or'|||). The upper pair of worms H2B-|21) are rigidly secured to avertical shaft, |33, which is rotatably mounted in bearings on thehousing cap 42h and in the lower base plate of the roll stand; and thelower pair of worms M30-|29) are an integral part of a tubular sleeve|34 which is slidably and rotatably mounted on the shaft |33. The shaft|33 and the sleeve |34 are provided with spur pinions |35-I 36, whichare rigidly keyed thereto, and are respectively engaged by a pair ofspur gears |31 and |38 that are detachably secured to each other andrevolve, asl a unit, on a short vertical stud shaft |39. The unit gearassembly (I 31-l38) is in turn connected to any suitable driving motorby the mitre gears |40.

It is apparent that the above described arrangement of worm and spurgear elements permits each pair of worms to move axiallyi. e.tangentially with respect to the associated worm wheelsas they arerevolved by the parallel gears |35|36|31 and |38; and that this freeaxial movement allows each connected pair of worms (H6- |21 or |30-I29)to "hunt a position in which equalized amounts of power will betransmitted from the backing roll gears |4b-I5b- |24|25 to the sleevegears 9b and |0b at the opposite ends of the working rolls lb and 2b.This automatic balance, or equalization, of the driving forces (toothpressures), exerted at the separated zones of gear engagement betweenthe positively driven backing rolls 3b| |0 and 4b-|||, and the workingrolls Ib and 2b, is obviously of marked advantage in eliminatingunequally distributed stresses and strains in the operating elements,and in greatly reducing any tendencies to twisting, or angulardistortion, of the small diameter work rolls. v

The lower intermediate spur pinion I31-which is operatively integralwith the horizontal mitre gear |40-is provided with an upwardly extendedsleeve hub that carries the upper intermediate pinion |38; and thecontiguous faces of the two pinions, |31 and |38, are each provided witha ring of teeth that are normally held in interengaged relation by thesleeve nut |4|. When the bracket support |42, which engages the upperend of the stud shaft |39, is removed, the nut |4| may be turned back,and the gear |38 may then be lifted and rotated with respect to the gear|31. This will, in turn, rotate the lower set of worms |29-|30, withrespect to the upper set IZB-|21, and will correspondingly alter theangular position of the lower gear driven work-' ing roll 2b withrespect to the upper working roll ib. These two rolls may thus bebrought to such a relative angular position that the gear teeth on theupper roll sleeves'are out of operative contact with the contiguous gearteeth of the lower roll (as shown in Fig. IV), so as to leave each rollto hunt its proper axial position with respect to its associated backingroll elements.v

In addition to the positive helical gear connections between the rolls,3b| |0-|b, and

4b| I-Zb, I may also provide a system of steelbelt connections betweenthese revolving members, which are similar to those already described inconnection with the organization of Figs. VII to XV inclusive. In theconstruction now being ,considered the belt engaged end collars of allof the rolls are reduced in diameter by the same proportionate amount-e.g. by approximately 13 %so that the ratios of angular velocityestablished by the belt connections are the same a's those that arefixed by the positive gear engagements. The twin belt elements b whichinterconnect the upper backing rolls with the working rolls pass fromthe upper side of the roll collars ||2a on the backing roll 3b, under apair of tension rolls |45, to the end collars ||2b on the secondarybacking roll ||0; then forward around the reducedouter ends of the upperworking roll sleeves 9b|0b; then downward and around the alignedportions of the associated sleeves on the lower work roll 2b; and thenforward again to the backing roll collars ||2a. The corresponding beltconnections (89h) between the lower backing rolls 4b and and the workingrolls IIJ-2b, run from the lower side of the end collars (I |2a) on theroll 4b, over anotherpair of tension rolls |46, to the end collars |2bon the roll then forward and around the lower work roll sleeves (in acounterclockwise direction); then up and around the upper work rollsleeves (in a clockwise direction); and then forward again to the lowerbacking roll collars |2a. Each work roll is therefore engaged and drivenby all four of these belt connections; and each belt is driven by itscir- (at its opposite outer extremity) onl a suitable bracket I carriedby the housing caps 2b-42h; and the other two of which MS2-|52) arerattached to the main base plate of the roll stand. Each set of carriageactuating leversat the opposite ends of the roll assemblyis operated bya connecting rod, |53, whose length can be adjusted by a centralturnbuckle, |55, so as to concurrently move the associated pair oftension rolls ISI- |52 toward or away from each other, and thus imposeany desired tensions on either pair of driving bells 6917-9017.

If we assume that the spreading pressure on the working rolls Ib and 2bis exerted in a vertical plane (which is approximately true in all casesexcept those involving abnormal draft reductions) the radial thrust onthe axes vof the backing rolls 3b and 4b will be about '78% of thisspreading pressure, and. the accompanying radial thrust on the axes ofthe associated backing rolls and will be approximately 63.4% The totalpressure which is effective in thev nonslipping frictional transmissionof power from the larger to the smaller rolls is thereforeunder the sameconditions as before assumed-supra:

(H. P.)= 0.5 (0.78 -i- 63.4= l.414) 20,000 X coca/33,000

g257.`per inch of width of roll pass g5l40 H. P. per 20 inches of widthIn addition to this we have the power transmitted by the helical geartrains which, in the case of the construction now being described (inline speed of 600 ft. per minute- (H. P.) grr-180 H. P.`

The total driving force on the working rolls of the last described mill(operating under the above specified conditions) will therefore be (H.PJM-(H. P. g+ H. Pana-5570 H. P.

Figs. XXIII to XXIX, inclusive, illustrate another application of myinvention to which I have hereinbefore referred to as a full cluster"type of mill, in which each working roll |c and'2c is provided with atwin pair of large backing rolls, 3c-3c and 4c--40, of the samediameter; and in which a set of four transmission rolls |60, |60c, |6|and |62, are interposed between each working roll and its associate pairof backing rolls in such manner that eachy assembly of revolvingelements, yIc|60|60c|6| and |62, or 2c- |60-|60c-'|6| and |62, issuported, in otant equilibrium, and in true vrolling contact, with thecorresponding pair of backing rolls 3c-4c or Ic-4`c. The geometricalrelationship between the roll axes, by which these results are attained,is best indicated in the .diagrammatic showing of Fig. XXIX; wherewb-wbare the lines joining the centers ofthe work roll |c and of the backingrolls 3c-3c;` wt-wt are the lines joining the centers of this work rolland of the transmission rolls |60c and |60; and :rb-.rb are the linesjoining the centers of the roll |62 and of the backing rolls 3c-3c. Asindicated by the arrows all (ISI or |52), two of which (|5||5|) arey Itwill be apparent that the thereof .j

of theV engaged surfaces of these devolving elements are in true rollingcontact with each other. conditions of stable or constrainedequilibrium, and of true rolling contact between the assembled rollswill be main-Y tained for any roll diameters which may be selected,provided onlyfthat the lines wt-wt lie inside (e. g. above) the lines10b-wb, and the lines, :cb-:rb are inclined to each other at an angle ofless than 180 degrees.

Each of the main backing rolls 3c-3c and 4c-4c comprisesa heavycylindrical shell |63, that is revolvably mounted on a stationaryjournal member I 6c whose reduced end portions are embraced and guidedbetween the side anges of the channel shaped housing pillars c-20c (or2|c2|c), and whose central portion is reversely coned to receive twocorrespondingly tapered split bearing sleeves ||1c-||1c. These bearingsleeves are provided at their outer ends with a series of inwardlyextending lugs |65,

which are positioned in suitable recesses in the shoulders of thejournal members |6c, and which are threaded to engage the extremities ofthe right and left hand screw bolts ||8c| |8c, etc., that are looselyheld in longitudinal slots on the surface of these members. By turningthese bolts the split bearing sleeves ||1 c-| 1c may be moved axiallyontheir coned journal seats, and thusexpanded (or contracted) to obtainand maintain the desired clearances between the bearing surfaces.

The radial openings surfaces of the sleeves ||1c and the internalsurfaces of the outer revolving shells, |63, are, in this case, filledwith rows of segmental bearing between the external shoes, |66, 66,etc.-(as here shown seven in number)-each of which is provided with twoend trunnions |61|61 that are engaged in short g radial slots in theannular spacing rings |68, |69.

One of these spacing rings (|68) is held in fixed.

endwise relationship to the adjacent extremities of the trunnions |61,by the cap screws |10; but the other ring (|69) may be adjusted axiallywith respect thereto, and clamped in this adjusted position, by thedouble lock nuts |1|. Each trunnion element |61 carries a roller |13,which is of oval cross section, and is engaged, on its inner side, bythe beveled ange surface of a ring |14 that is clamped against theshouldered end of the stationary journal member |6c, and, on its outerside, by an internally coned end portion |15 of the outer revolvingbacking roll shell |63, see Fig. XXVI. The outer ends of these shoerollers, |13, are engaged by the adjacent spacing rings |68 and |69; andby moving these rings toward each other (in the manner alreadyexplained) the rounded faces of the rollers may be wedged, more or lesstightly, between the reversely coned surfaces of the rings |14 of theshell |69.

When the backing rolls 3c (or 4c) are rotated, the members |13 arerevolved on their trunnion- .the more rapidly advancing bearing surfaceof the backing roll shell |63, and also between their inner faces andthe stationary outer surfaces of the bearing sleeves ||1c (see Fig.XXV). This system of individually tiltable shoes with end rollersupports, is comparable in effect with the well known Kingsburyend-thrust bearing which has a lower coe'mcient of running friction thanany other bearing known; and the use of the auxiliary rollers |13 incombination therewith also substantially reduces the starting friction(as compared with that of a plain cylindrical bearing), and ensures thecontinuous relative movement between the shoes and the bearing surfaceson which they are floated by the intervening oil films.

Each of the backing roll shells |0| is provided, at one end, with alarge spur gear |11 whose pitch diameter is the same as that of theouter surface of the shell, and which is capable of receiving andtransmitting at least one-fourth of the maximum power that is employedin operating the roll stand.. 'I'hese gears are driven in unison-torotate the upper backing rolls 3c-3c in one-direction (e. g. clockwise),and the lower backing rolls 4c4c in the reverse directionby a pair ofpinions |18|`|8 which are of the same pitch diameter as the outerintermediate rolls |62|62, and are preferably made integral therewith.The adjacent ends of these rollsare extended outwardly (as' best shownin Fig. XXVII) to receive a pair of involute tooth mill gears |80|80,which are in mesh with each other, and which are driven by any suitablemeans--such as the wobbler pinion |8| indicated in dotted lines in Fig.XVIII. Each of. the rolls |82 is also provided with two rings |02|82 ofoppositely inclined helical gear teeth, of the same pitch diameter, butof ner pitch, than the spur pinions |18; and these gears |82|82 areengaged with similar gears |83|83 on the intermediate rolls |6|-|6|.Each of the gears HB3-|83 is engaged with two gears |84|84c on the rolls|60 and |600; and the latter are in turn in mesh with the working rollsleeve gears 8c-|0c, see Fig. XXVII. The pitch diameters oi all of thegears |83, |84 and |84c are (like the gears ETF-|78- |828c and |0c) thesame as the outside diameters of the corresponding roll members; and theengaged surfaces oi these revolving elements are thus maintained in truerolling-on-slipping relationship to each other.

Each pair of backing rolls (3c-3c and 4o4c) are connected to theassociated working roll (Ic or 2c) by a pair of steel belts 80c--80c and890-890, which also pass around the cylindrical outer ends of therollers |60|80c and thence under (or over) the adjacent extremities ofthe gear sleeves 8c-|0c. In order to permit the use of these belts,withoutextending the last. mentioned rolls beyond the ends ofthe rollsIGI, the gears |84 and |84c-and the cooperating gears on the work rollsleeves 8c and |0c-are of less width than the gears |82-|83; and theoutlet belt engaging sections of the rolls Ic-Sc (or 4c-4c) |60-|60c,and of the gear sleeves 8c|0c are all reduced in diameter, by the sameproportionate amount (in this case about 688%). in order to permit thebelts to pass over and be-v tween the teeth on the adjacent rolls ll-|62(see Fig. XXIX). The belts 80e pass from the top of the front backingroll 3c, under a pair of paper tension rolls, |45c|48c to, and aroundthe rear backing roll 3c; then forward around the transmission roll|60c, then downward and around the upper working roll |c;' then up andaround the transmission roll |60; and thence forward again to the lowerside of the front backing roll 3c. The belts 880-880, follow a similarpath (over the lower tension rolls |48c, around the rear backing roll4c, the lower transmission roll |800, the bottom working roll 2c, theadjacent roll |80, and forward again to the front backing roll 4c); andboth sets of belts .8c-88e and 80c-8lc perform the joint functions oftransmitting power from the positively driven backing rolls to theworking rolls-(and in this case to the intermediate rolls IED-|60() aswell and of also maintainingall of these rolls in operative relationshipt0 each other when the mill is running idle, and there isI no spreadingpressure exerted on the floating roll systems Ic (or 2c) |80|60c-|6| and|02.

Each of the tension rolls |45c|45c is rotatably supported in-abifurcated frame |88, which is secured to a tubular sleeve |86 that ispivotally mounted on the cross shait4 |81; and is provided, at the outerend of the sleeve |08, with a fork arm lever |88. The lower tensionrolls |48c|48c are similarly mounted on a cross shaft |88 that iscarried by suitable supports on the base of the roll stand, and areconnected to forked arms |80-|80. The ends of each pair of arms IBB-|80(on theopposite ends of the roll assembly) are connected by the pivotedlinks |8|-|8|; and

ends are engaged with the said links, and which can be rotated, by anysuitable means, to impose any desired, and automatically equalized, ten-I sions on either set of belts, 88-80.

In order to transmit balanced amounts of power from the positivelydriven transmission roll |62 to the associated Working roll |c (or 2c)the helical gears |84 are mounted to move freelyboth circumferentiallyand axially-on the ends of the rolls |60, so as to permit them toautomatically hunt positions in which the tooth pressures between thesegears and the sleeve gears 8c|0c are substantially equal to thosebetween the latter and the gears |840. One of the driving gears |80 isalso connected to the roll |82, in such manner (as indicated in Fig.XXVII), that it may be turned slightly thereon, and then rigidly clampedthereto (e. g. by the hub bolts |83) see Fig. XXVII, so as to keep thehelical gear teeth elements of the two working rolls, icl-2c, out ofcontact with each other (as shown in Fig. IV), and thus permit each ofthese rolls to move axially-independently of the otheruntil the drivingpressures on the oppositely inclined helical teeth of these elements arein balance.-

As has already been pointed out each set of.

transmission rolls, |60-|60o-|0| and |62, are automatically in vfixedrelative relationship to each other and to the backing rolls 3c-3c (or4c-4c) both by the reactive rolling pressures on the working rolls |cand 2c, and also by the tension of the belt elements 80c-80c andBSc-88e; and no auxiliary end bearings for these rolls are required tomaintain this true rolling relationship between them, either while themill is running idle or when it is operating.

But in view of the fact that all of the driving,

25 the tension rod |53c, whose reversely threaded 4 in, or carried by,transverse chock blocks |91 which are rigidly bolted to theadjacentsidesv made of slightly larger diameter than the overall sizeof thegears or, as here shown, are provided with free bearing sleeves |99, ofthis requisite diameter. Any one, or all of the other small rolls(|c-2c-l60-I60c and |6I), can be removed and replaced from the front(left hand) end of the roll stand by merely lifting the upper set ofbacking rolls 3c--3c by a small amount and by relievingthe tension onthe belt connections 09a-90e.

In the constructionnow under consideration the lower set of backingrolls lc-Ic are supported in fixed position by the usual form ofleveling (wedge) plates and set screws (200); and only the upper set ofbacking rolls 3c-0c are moved up and down-to change the height of theroll passby the conjoint action of the four holding down screws, and ofthe heavy lifting springs 202 that are interposed between the ends ofthe journal members |6c. The holding down screws 20| are threadedthrough the ends of the housing caps 42o-I2C, and are leach providedwith a bevel gear 204 which is engaged by apinion 200 on the adjacentend of a shaft 200, that is provided, at its center, with a worm wheel201; and the two worm wheels, 20L-201, at the opposite ends of the'rollassembly, are cross connected by the worm and worm shaftv elements208-209-200. Allfof these parts, 205-200-201-200-209, are supported bybearing members 2|0-2Ii, which are mounted on, and move up and downwith, the shouldered ends of the holding down screws 20|.

.so that all of the gear elements are automatically maintained inengagement for all positions of the upper backing rolls. 'I'he wormshaft 209 is made in two coaxial sections, which may be connected ordisconnected at will by a central clutch 01e; and each of the bevelpinions 205 is axially movable on its splined shaft 206,.so as to permitit to be thrown out of engagement with its associated gear 205, by meansof a shift lever 2 Il. The two pairs of companion screwsV 20|-20I maytherefore be rotated concurrently or independently, or any one screw maybe moved independently of all of the others, to adjust the axes of thebacking rolls to any desired position.

, In order to assist the action of the springs 202',

the screws 2|0 may be axially bored to receive lifting bolts 2|0, Fig.XXIII, which pass down through. the journal members |00, and arerotatably engaged at their upper ends with the adjacent extremities ofthe holding down screws.

When the nuts and washers on the upper ends of 'these lifting bolts(2|0) are removed and the connections the chock block members |00 fromtheir housing support 20c-lic,

The vertical movement of the upper backing rolls, to change theheight ofthe roll pass, will alter the center to center distance of the drivinggear |00|00, but the involute form of tooth permits -this to be donewithot interfering to any material degree with the efficienttransmission 'of powerfrom one to the other. All of the other geartrains remain in fixed center to center relationship, and may thereforebe provided with either the 'involute or the epicycloidal form of toothsection. n

The provision of the auxiliary bearing "members |95-l 90, for the endsof the positively driven Vtransmission elements |02--|62,4 not onlyassists these elements in maintaining a true rolling relationship withthe surfaces of the associated rolls 3c, 4c, and 0|, (and in resistingyany side orend thrust of the engaged gear elements |11|10 |00-i02 and|00), but also affords a convenient channel in the bearing block |91,and this channel is connected, by two branch passageways, 22|, withlongitudinal passages 222 in the connected journal members |0c, whichare, in turn, provided with a series of lateral ducts leading to theopenings between the edges of the split bearing sleeves ||1c, at a pointabout 90, degrees in advance of the planes of radial thrust on thejournal axes (see dotted lines of Figs. m and XXIV). The annular channelin the bearing member |91 is also connected-by the extensible pipeconduit 22S- with a like system ofnassageways vancl ducts in the lowerbearing block |60 and ir the journal supports for the lower backingrolls lo-lc. This engagement ensures a continuous and copious flow oflubricantunder pressure if desired-to all of the enclosed bearingsurfaces ofthe roll assembly; and, as before indicated. the design ofthe main backing roll bearings is such that the maximum unit pressuresthereon are well below the rupture point of the supporting oil films.

In the illustrative construction shown in Figs. XXIII to XXIX the anglebetween the vertical and the planes w-b, w-b is a little less than 51degrees, and the axial thrust on each of the backing rolls is thereforeapproximately '19% of the vertical spreading pressure on the workingrolls Ic-2c. on the latter is therefore about 60% greater than thatwhich is exerted by the action of the two backing rolls of a four highmill, such as is shown in Figs. I to VI inclusive; and under theconditionsheretofore assumed will amount to at least 5800 H. P. Inaddition to this we have, as before, the supplemental driving effects ofthe helical gear connections between the rolls |62 and |c2c, and of thebelt connections between the latter and the rbacking rolls 0c3c0clc; andthese may aggregate (as before indicated) from 300 to 400 H. P.

In mills of the cluster type the ratio between the substantiallyvertical (or normal) spreading pressures on the working rolls, and theresultant radial pressures on the backing roll surfaces in .engagementtherewith increases very rapidly as the angular separation of thebacking rolls- (i. e. the-angle between the lines w-b, 11i-b)- isincreased. In asymmetrical 60 degree ar- The total frictional drivingeffect rangement-in which the lines Joining the center of a workingvroll with the centers oi. the two associated backing rolls make anyangle of degrees with -the vertical-the component of radial thrust oneach of these backing rolls is substantially equal to the spreadingpressure on the working rolls; and the total pressure of surfaceengagement between the driving and the driven elements-which determinesthe limit of power transmission through such engagement-is twice thatwhich it is possible to obtain in a straight four high mill assembly,and very substantially in excess of that obtainable with semiclustermills suchas are shown in Figs. VII to XXI inclusive. But in all cases`the amount of power which may be transmitted from th'e positively drivenbacking rolls to the small working rolls, by a non-slipping pressureengagement between the roll surfaces, is amply suiilcient to operate themills of my improved construction under the heaviest drafts and at thehighest speeds now attainable with much larger working elements.

'I'he various forms ofconstruction which have been heretofore described(as illustratedin Figs. I to XXX, inclusive) are particularly designedfor use as continuous-or one way-mills; but it will be apparent-that theroll assemblies shown in Figs. XVII to XXX may be used, if desired, inreversing y'(or two way) mills. The organizations illustrated in Figs.VII to XV can also be used in two way rolling; and the constructionfirst described (Figs. I to VI) may bel easily modifled to operate as areversing mill. But the arrangement which I prefer to employ in mills ofthis character' is shown in Figs. XXX to XXXI inclusive where Id, 2dindicate the small working rolls, 3d, 4d the two corresponding backingrolls, and 225-225 are a pair of power receiving land transmittingrolls, which are interposed respectively between the'rolls Ici-3d and2d-4d. The axes of all of these rolls 4are positioned in the samevertical plane XIVI-XXX, which is perpendicular to the line of movementof the material through the roll pass.

The backing rolls 3d-4d are each mounted on a ring of segmental bearingshoes |6611, which are revolvably engaged with tapered bearing sleeves||1d, that are axially adjustable on the stationary journal members|6d;-the construction and arrangement of these parts being substantiallythe same as that previously described (see Figs.

' XXW to XXVI, supr-a). The ends of the journal supports, iSd, projectinto the window openings betweenV the two pair of housing pillars20d-2id, at the opposite sides of the roll assembly; and are cut away orrabbeted to receive stirrup shaped chock plates 226 which are boltedrigidly thereto, and which are slidably engaged at their edges with thecontiguous faces of the pillars 20d-2 Id. The adjacent portions of theseplates are cut out to form open semi-cylindrical guides for the ends ofthe rolls 225; and the action of these end guides is supplemented byV-shaped cross head members 221-221 etc.; which extend across betweenthe plates 226-226 and are held in position by the through bolts228-229. These connected .members 226-221 provide continuous sidebearing supports which will -prevent any lateral displacement of thepower receiving and transmittingrolls 22S-225 under the side thrust ofthe main driving gears |d-|80d, which are secured thereto, and which aredriven in unison in any` suitable manner.

The opposite ends of the rolls 22S-225 are provided with oppositelyinclined helical gear elements "2d-Ind which engage with complementarygears 9d on the working rolls |d-2d, and which transmit automaticallyequallzed quotas of power thereto in the manner previously explained. Inorder to restrain any transverse movement of the working rolls 4underthe pull which they exert on the material passing between them I providetwo pair of symmetrically disposed castor rolls .230-230, which areengaged, on their inner sides with the working rolls |d-2d, and on theirouter sides, with two other pair or small .backing rolls 23|-23| thatare mounted in rolling contact with the driving rolls 22S-225. Eachgroup of `rolls 230--23|, 23d-23|. is supported in position, on oppositesides of the corresponding work roll (Id or 2d) by means of crossheads232-232, which are secured to the chock plates 226-226 by means ofthrough bolts 233-233, and cap screws 234, and which are also clamped tothe bearing members 221 by the screws 235. The inner faces of "the crosshead supports 232 are machined to form segmental bearing surfaces forthe rolls 23o-23|; andr in order to more eiectively resist the lateralspreading pressure on these surfaces, and to also ailord a means fortheir accurate adjustment, the ends ofthe through bolts 233 are crossconnected by toggle bolts 226.

In order to increase the amount of power that may be transmitted fromthe gear elements |82d on the rolls 225 to the work roll gears 9d, therolls 23|) and 23| are also provided with coengaging gear elements whichare respectively in mesh with the helical gears 9d and |82d; and inorder to equitably divide, or equalize, the driving thrust on the teethin the three lines or zones of engagement with the working roll gearsSd, the castor rolls 230 (like the working rolls idf-2d) are'left freeto move axially, and the cooperating gears on the ends of the rolls23|-like the gears |84 on the rolls |60 (see Fig. XXVII supra)- areformed on separate collars that can each move independently and hunt itsposition by balanced thrust, or driving action, on the rolls 230. Sincethe three zones of tooth engagement on the working roll elements 9d areseparated by an angular distance greater than the arc 'of tooth)engagement itself, it follows that the amount of power which can betransmitted to these elements, with the arrangement last described, is`three times as great as that which can be transmitted with theconstruction shown in Figs. I to VI, and is 50% greater than can beimparted vwith the arrangement illustrated in the upper part of Fig.XIV, and in the alternative arrangements of Figs. XVII and XXVIII. Underthe conditions above specied 'gears of 5 D. P. and 4" face can thereforebe relied upon to safely transmit a total iwf 180 H. P. to each workingroll-or 360 P. to the two-at a peripheral speed of 600 feet per minute.

An additional amount of power can be transmitted from thepowerj'eceiving and transmitting rolls 225 to the workin'g rolls Id and2d by means of th l,riferi belts ildiand 89d, which are engaged wit theplain e'nd portions of the rolls 311-23 |-230 |d-230-23i and 225 (or4d-23I-230-2d-230-23I and 225). As shown in Fig. XXX to XXXI the pair ofbelts Sd-d pass from its upper backing'roll 3d downward around a takeupor tension pulley |45d; then vunder the left hand supporting roll23i-(through a triangular slot 231 in the cross head 232)-then over andpartly around the 40 asbefore calculated, about 3600I P. for ar 20"A vso meager vadjacent castor roll 230 then under the upper working rollld; then over the righthand castor .roll 230 and under andjnearlyaroundthe adjacent supporting roll 23| then' under and around the uppery powertransmitting roll 225 and back to the upper backin roll 3d. The belts33o-#33d follow a correspon ng, path; over,`- underl and` around' alower tension roll ludl and the successive. rotating elements 23l230-2d+230. lof" smaller rolls ymoves with it. The spreading pressure towhich the working/rollsldh are' 23I'22i54d;` and the two tension rollsMld and Mid are supported on rocking frames 3Id which are .carried oncross shafts' l31d, and:`

whichcan-be drawn toward each other (toconcurrently subject thebeltsNit-30d ion each end of the roll assemblies to equalized tensions) by 'aturnbuckle connection 1531i. r At aworking tension of 2000 lbs., andlinear (peripheral) speed of 600 feet per minute pairg of belts Bild-881 or slid-Bild, can .trans-y 'l mit about 73 H, P.v to one loftheworking rolls;

or a total of approximately 145 H. P. to thel two. If we add this to thetotal H.P.' transmitted .by

the three vzone helical gear drives previouslyde'- scribed we 'have-anaggregate of over 500 H. Il.'

II- that may be imparted to the small working-rolls (M -2d) from'thepower receiving rolls 22! .iependently of any frictlonal `driving actionthat is obtained by the non-slipping pressure engagel ment between theserotating elements. thev.construction now 'under consideratlonf-where theaxes ofv the'engaged rolls ld v22l- 3d, and 2d-225 4 are allpositioned-in the same vertical planethe contact pressure between thedriving44 and driven elements is substantially l equal to the pressureof the working rolls on the materiahjand if this is 20,000 lbs. per inchof width (as previously'assumed) the'power transmitted by thenon-slipping frictional engagement of the roll elements 22S- ld and22B-2d is,

stripmill. This lis lless than that obtainedI in somev of the forms` oft "cluster mills previously described; but it is more than sufficient toIoperate a sixhigh'revrsing .mill of the character t 45 nowfunderconsideration. 'l 1 One of the advantages of-` thej construction .shownin Figs. XXX, XXXI afndXXXII is that the helicalfgears which communicatemotion to f ythe working rolls-and thus maintain them in non-slippingrelationship'to the power receiving rolls 225 are all of relativelyvsmall slze,'and are therefore less -expensive-toconstruct than the# ilarge gear elements li-I5, lla-lla, MU-IIb, or Ill-|11 with which` themainbacking'rolls g5 3 4, 3ft-4a, etc.v must be provided when thelatfter 'are in direct pressure engagement with'the lworking rolls; andare used to communicate pow.- er thereto. through the frictional grip ofthe engaged surfaces, 00 (225) is interposed between eachworking roll(la or zd) and the associated backing roll (3d or I vId), -it is ofcourse unnecessary vtov positively drive 'eitherl of the latterelemente-which in this case perform only the function of receiving-aiyan'dsu'staining the major part of the vertical 75 thereto, arerigidly secured as units to thejournal 23o-23D is therefore supported'in 'flied axial 'smallfpart ofY that pressureis re'ceivedy by the chockplatey and cross headbearing elements .z 28-221;' t he major partoflthis vload bein'g bearings of the main-'backing r umd-4d; The

c In thecase of a reversingmil nal supports ltdlare each provided withya central lin thesleeves themselveslr'I'he bearing surfaces of thecross heads 221 are 'continuously'suppliedf` When a 'power receivingroll `1:3 members lid; and that each setofy power tranii-y mitting andlsupporting' rolls t (22l-23l'239 relationship to theassociatedbackingrroll (3d or 4d); yand when either of theal'atter rollsiii;- moved .`'either by the'adiustmentjof the leveling plates f andscrews 2nd,' or by the holding down and lifting screws 20|d, 2|6dthecorresponding set subjects@ duringy the rolling of thematerial.- isfirst coihmunicatedto the power. ieceiving rolls 225;l initv theeinterco'nnected bearing supports I6d`-226221f`are so assembled thatonly a very transmitted to, and sustained/bypthejournal only lood` whichmust pe carried y the cross head bearing elements 2321?-232 is vthatproduced by alateral pressurey `on the castor rolls 2301-230 Y and .on/the associated supporting rolis freiem;

and a substantial component of the pressure |is sustained bythe rollingco ntact of theelements 23| on-the largerrolls225. i

l--fwhere tle rolls, revolved nrstin one directio/n 'and then in theother. provisionmust be"m`ade lfor introducing lubricant at both sidesofthe roll bearings, IIn the Iconstruction here illustratedthebakingrolliiour-l longitudinal kpassagewayv dJ-which is supplied withoil from an outside reservoir (not shoWnY-- and with a series ofradially disposed ducts' 52d 35 that'lead to two of thepocketsoi`grooves,in which the vjournalsleeveloolts Illd are located (see Fig.1K2!) ,t and from -which the oilpasses to the bearing surfaces throughsuitable 4perforations with lubricant f rom `the hollow through bolts fv.22S-##229, and suitable ducts leading therefrom to the edges ofthebearing b1ocks;'and the revolving elements 23 I ,and 230 are also'ushed with oil from one of the 'tubular bolts 22s ondlongitudn nalpassageways 60d inthe cross heads 232. In this ,construction-as in allof those previously 'consideredthe design is such that the unit pressureon any baringsuriace is well within the n limit of rupture pressure ofthe oil ilim; and when adequate provision is made/for the festablishmentand continued maintenance offthis l there-is no advantage t9 begaineurabut-o the contrary there is a disadvantage to be met by.v asubstitution of ball or roller bearings in plaqe of the plaincylindrical journal'bearings herein' described. i It is alsowelllunderstood by those skilled in, the rolling art that thev spreadingpressure on the working rolls, and the powerrequired to drive them atany given speed, is not only decreased by reducing the vfsize of theserolls,'but also by applying a .tension to the material passing betweenthem. This tenson may^be eitherra for-U ward (or positive)one--whichftends to-pullthe material through the roll passor 'a backward(or negative) one-which tends to retard the forward movement-or better-still a combination of both positive and negative `tensions. In the 70

